Automatically adjustable ladder



0a. 12, 1948. K. v. OZOLS 2,451,113

AUTOMATICALLY ADJUSTABLE LADDER Filed Aug. 9, 1945 IN V EN TOR.

KAHLIS OZOLS BY WWa ATT Y Patented Oct. 12, 1948 UNITED STATES PATENT OFFICE AUTOMATICALLY ADJUSTABLE LADDER Karlis V. Ozols, Brooklyn, N. Y.

Application August 9, 1945, Serial No. 609,751

6 Claims.

The invention relates to ladders and particularly to step ladders to be positioned on uneven or inclined localities or bases.

To solve this problem various devices have been suggested mostly based on the use of vertically displaceable compensating and extension members, the displacement of these extensions being frequently effected by the cooperation of racks fastened to the ladder and pinion wheels provided on the ladder legs.

It is the primary object of the invention to render the adjustment of the ladder legs by means of extension members and the positioning of the ladder on uneven localities and bases automatically operative.

It is another object of the invention to effect the automatic compensation of uneven localities upon which the two ladder legs rest by the Weight of the ladder legs.

It is also an object of the invention to automatically secure the ladder in the level compensating position.

It is another object of the invention to provide a ladder which upon being lowered from any point onto uneven locality will automatically assume and retain the position in which it may be stationed and will be secured in the same.

A further object of the invention is to provide a step ladder which in addition to the above described advantages will be efficient, durable, inexpensive in manufacture and at the same time simple in construction and operation.

With these objects in view the invention will now be described in detail and with reference to the accompanying drawings, in which identical elements are denominated with the same numerals.

In the drawings,

Fig. 1 is a fragmentary vertical side elevation of one ladder leg,

Fig. 2 is a vertical fragmentary side elevation of the other ladder leg,

Fig. 3 is a fragmentary vertical front elevation of the ladder, the leg ends being shown in section on line l|. and 22 of Figs. 1 and 2,

Fig. 4 is on an enlarged scale a horizontal section on line 3-3 of Fig. 3.

Referring more particularly to the drawing, I and 2 denominate the lower ends of the two ladder legs, which are connected by rungs 3.

Leg is provided with a distance compensating member 5; this member 5 is in the present embodiment of the invention shown to partly encircle ladder leg I, and is made vertically displaceable in relation to the latter.

Member 5 is provided with two outwardly projecting vertically extending edges 29, 30 whose inner faces are shaped to form racks 5 and Illhaving teeth of equal pitch. The operating face of rack 6 is wider than that of rack 10, as apparent from Fig. 4.

A horizontal shaft 8 is mounted by means of sleeves 3| in the ladder legs; that part of the shaft passing through leg I is enlarged to form a square shaped head l5; the square shaped enlargement l5 prevents shaft 8 from rotatin Within the ladder legs, but does not prevent its horizontal displacement or reciprocation on slide bearings 3|.

The one end of shaft'8 outwardly projecting from ladder leg I carries a pinion wheel I which is loosely rotatable thereon, but may be prevented from being displaced in axial direction on or in relation to shaft 8; in other words, wheel I cannot move in axial direction independently of shaft 8, but it is displaced when the shaft is reciprocated in the axial direction.

Shaft 8 is normally so located in legs I, 2 that pinion wheel 1 is in constant meshing engagement with the outer portion of the wider rack 5; therefore, the distance compensating member 5 can freely reciprocate in vertical direction, the pinion wheel I rolling along in coaction with rack 6. If, however, shaft 8 is displaced in the direction of arrow S, pinion wheel I engages the opposite rack Ill which will result in a stoppage of the hitherto free displacement of extension member 5 and immobilize the same in the corresponding position.

A slot 9 is provided in the distance compensating member 5, the upper and the lower end of the slot to be used for limiting the reciprocation of member 5 in its vertical direction.

A hollow extension 12 is inserted in the lower end of distance compensating member 5; the latter is rendered vertically displaceable in relation to extension l2 by means of bolt 33 mounted in member 5 and slot I3 provided in extension 12. Extension 12 is supported in member 5 on spring 3 M, which is inserted between bolt 33 and the bottom 2| of extension H.

Shaft 8 is, at the end opposite the distance compensating member 5, provided with a threaded portion 20; the latter cooperates with pinion wheel l9 secured on the threaded shaft portion 20. This pinion wheel [9 is provided with teeth on its periphery meshing with rack l8 of rod l1. The lower end of ladder leg 2 is reciprocally inserted into a hollow extension I6 and supported on spring 22 located in the latter.

A rod I'l extending alongside the lower end of that the ladder is to be positioned on an'inclined locality in such a manner that leg I will have to rest on a lower level than leg 2.

The ladder is set on this locality. The distance compensating member 5 will slide down by gravity over leg I from a normally secured position, whereby the larger rack 6 freely passes along rotating pinion wheel 1.; the latter does not mesh with rack I during this initial stage of the ladder adjustment. When" compensating member reaches the lower level point, its weight partially compresses spring [4 and extension l2 moves for the same distance into the compensating member.

Now the ladder legs movedown along compensating member 5 until extension l6 strikes the ground' The weight of the ladder compresses spring 22. and leg 2 moves down accordingly: consequently pinion wheel I9 is set in rotation by engagement with rack'lB of rod 'l'l supported on the ground; by the rotation of wheel [9 the threaded portion 20 of shaft '8' is accordingly rotated; shaft'a is displaced in the direction of arrow S and pinion wheel 1 is now moved in co action with rack'lfl'; at this moment pinion wheel 1 is engaged by both racks and its further rotation is stopped. a

During the last stage of the operation rack I8 continues to rotate pinion wheel IS on the threaded end of shaft 8; accordingly pinion I is completely moved between racks 6 and Ill, whereby the ladder is automatically locked in the oper-. ating position.

I claim: I 1. A ladder for use on an uneven locality comprising an extension foot attached to the one ladder leg, said foot being freely displaceable' along said ladder leg, a shaft transversally shiftable in the two'ladder legs, a pinion wheel rotatably carried by the one end of' said-shaft, parallel racks of different width carried by said extension foot to be successively'brought in meshing cooperation with said pinion wheel, means con-'- necte'd with the other ladder leg to displace said shaft'and said pinion wheel upon arrival of the ladder in its operating position and to thereby effect the meshing cooperation of' said' pinion wheel with both of said racks to thereby stop the free displacement of said extension foot and to lock the same in the thus adjusted position.

2; A ladder for use on an uneven locality comprising a distance compensating member movably attached to one ladder leg and lowerable by gravity along the same, an extension resiliently the ladder upon its location in the operative position, means operative upon the downward movement of said leg to automatically stop the displacement of said compensating member and to lock the same and the first ladder leg in the thus adjusted position.

3. A ladder for use on an unevenlocality comprising a distance compensating member movably attached to one ladder leg and lowerable by gravity along the same, an extension sleeve closed at its lower end and accommodating the lower end of the second ladder leg, a spring between said closed sleeve end and the lower end of said leg'adapted to be compressed bythe weight of the ladder upon its location on' the operative position and to lower said ladder leg into the sleeve, means operative upon the downward movement of said leg to automatically stop the displacement of said compensating member and to lock the same and the first ladder leg in the thus adjusted position. 7

4. A two-leg ladder for use on an uneven locality comprising a distance compensating member movably attached to onefladder leg and lowerable by gravity along the saine, a shaft transversally shiftable in' both ladder legs, a pinion wheel rotatably-carried by the one end of said shaft, parallel racks of diiferent width carried by said compensating member, meansto'successively' bring said racks in meshing cooperation with saidpin ion wheel, said means including a second Pinionwheel carried by the other end of said shaft,

means connected with the second ladderrleg operative upon the weight of the ladder to rotate.

pinion wheel carried on said shaft ismoved intg meshing cooperation with both racks to stop -further displacement of said compensating'memberv member carrying leg'bei'ng enlarged toforrn-a square-shapedhead'preventing rotation of said shaft but permitting its" transversal movemenca pinion wheel rotatably carried by the one end of said shaft, parallel racks jof difierent width carried by said compensating member, ineansto successively bring said racks in meshing coopera- 7 tion with said pinion wheel, said means including a second pinion wheel carried by theother end of said shaft,.means connected with the second leg operative upon the weight of the ladder to rotate said pinion wheel and to transversally. move said shaft upon arrival ,of. said leglin the operating position of the ladder, whereby said first pinion wheel carried by the shaft is'movea into meshing cooperation with bothv racks to stop further displacement of said. compensating member and said first leg and to lock the same in'the thus adjusted position. 1 I

6. A two-leg ladder for use on an uneven locality comprising a distance compensating member movably attached to the one ladder? leg and lowerable by gravity along the same, a shaft transversally shiftable in both ladder legs; a pinion wheel rotatably carried by the one' end ofsaid shaft, parallel racks of different width carried by said compensating member, means to be successively brought in meshing cooperation with said pinion wheel, a second pinion wheel carried by the other end of said shaft, an extension re siliently connected with the lower end of the second ladder leg, a hack attached to said extension in meshing engagement with said second pinion wheel adapted to rotate the latter and to displace said shaft transversally upon arrival of said leg in the operating position of the ladder, whereby said first pinion wheel carried by the shaft is moved into meshing cooperation with both racks to stop further displacement of said compensating member and said first leg and to lock the same in the thus adjusted position.

KARLIS V. OZOLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 970,425 Curran Sept. 13, 1910 2,293,188 Brice Aug. 18, 1942 2,366,829 Biery Jan. 9, 1945 

